A new study provides strong evidence that a hazardous class of flame retardant chemicals, known as polybrominated diphenyl ethers, or PBDE, damages children's intelligence, resulting in loss of IQ points.
Published this week in Environmental Health Perspectives, the study by researchers at the University of California, San Francisco, goes beyond showing a strong correlation between PBDE's effect and children's intelligence by including the largest meta-analysis performed on flame retardants to date.
Using rigorous epidemiological criteria, the authors considered factors like strength and consistency of the evidence to establish that there was "sufficient evidence" supporting the link between PBDE exposure and intelligence outcomes. They examined data from studies covering nearly 3,000 mother-child pairs, and discovered that every 10-fold increase in a mom's PBDE levels led to a drop of 3.7 IQ points in her child.
Acknowledging that a 3.7-point decrease in IQ might not sound like a lot, lead author Juleen Lam, an Associate Research Scientist at UCSF's Program on Reproductive Health and the Environment (PRHE), noted that on a population-wide level, it means more children who need early interventions.
In addition, the researchers found some evidence of a link between PDBE exposures and attention deficit hyperactivity disorder (ADHD).
PBDEs are commonly found in furniture and household products. They first came into widespread use after California, a state on the U.S. West Coast, passed fire safety standards for furniture and certain other products in 1975. Due to the size of the Californian market, flame retardants soon became a standard treatment for furniture sold across the United States.
PBDEs and similar flame retardants are not chemically bonded to the foams they protect. Instead, they are merely mixed in, so can easily leach out from the foam and into house dust, food, and eventually, human bodies. Evidence of PDBEs' danger prompted reconsideration and starting in 2003 California, other states, and international bodies approved bans or phase outs for some of the most common PBDEs.
Less than two weeks before the UCSF study's release, legislation was introduced in the San Francisco Board of Supervisors on July 25 to ban PBDEs and all other flame retardant chemicals from furniture and children's products sold in the City and County of San Francisco.
The UCSF researchers have posted guidelines for avoiding PDBEs during pregnancy on PRHE's website.